This review concluded that there was not enough evidence to recommend using methods to increase muscle tonus of upper airways in the treatment of snoring. The conclusion was appropriate and likely to be reliable, despite some concerns regarding the review methodology.

Authors' objectives

To evaluate the efficacy of methods to increase muscle tonus of the upper airway to treat snoring.

Searching

The Cochrane Library, MEDLINE via PubMed, LILACS, EMBASE and SciELO (Scientific Electronic Library Online) were searched to September 2007; search terms were reported. Theses indexed at Biblioteca Regional Medicina/Panamerican Health Organization of the World Health Organization and the reference lists of relevant articles were checked for additional studies. Authors of primary studies were contacted for additional information. No language restrictions were applied.

Study selection

Randomised and quasi-randomised controlled trials that compared any method to increase muscle tonus of the upper airway to placebo, no treatment or another alternative treatment in participants with snoring were eligible for inclusion. Studies that included participants who met any clinical criteria for snoring were eligible for inclusion. The review listed a large number of participant exclusion criteria and studies that recruited participants predominately from these groups were excluded. Primary outcomes were a reduction or complete cessation of snoring assessed on a validated scale; secondary outcomes were sleep quality, quality of life and adverse events.

The authors stated neither how the papers were selected for the review nor how many reviewers performed the selection.

Assessment of study quality

Study quality was assessed using the following criteria: method of randomisation; allocation concealment; blinding of participants, researchers and outcome assessors; and similarity of comparison groups including withdrawals.

The authors did not state how many reviewers performed the validity assessment.

Data extraction

The authors stated neither how the data were extracted for the review nor how many reviewers performed the data extraction.

Methods of synthesis

No synthesis was undertaken.

Results of the review

No studies that met the review’s inclusion criteria were identified.

This review briefly reported the findings of a case-series (n=20). The intervention in this study was singing exercises. The study found some improvement in the mean amount of snoring post-treatment (5.1 minutes per hour) compared with pre-treatment (6.1 minutes per hour). The review also provided details of two randomised controlled trials that were yet to be completed.

Authors' conclusions

There was not enough evidence to recommend using methods to increase muscle tonus of upper airways in the treatment of snoring.

CRD commentary

The review addressed a clear question with well-defined inclusion criteria. The authors searched a number of relevant sources without language restrictions. Some attempts were made to locate unpublished material, which reduced the potential for publication bias. Methods used for study selection were not described, so it was impossible to rule out reviewer bias or error.

Given that the authors were able to identify only one case series, it was clear that the authors' conclusion and recommendations for further research were appropriate and likely to be reliable, despite some concerns regarding the review methodology.

Implications of the review for practice and research

Practice: As no studies that met the review’s inclusion criteria were identified, there were no implications for practice.

Research: The authors stated that well-designed randomised controlled trials were needed to evaluate methods to increase muscle tonus of the upper airway and that these studies should follow internationally published guidelines for reporting. They also stated that a standard and worldwide accepted method for snoring assessment would be of benefit to future researchers.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.